Direct-current-voltage transformer with series excitation.



D. @Ummm Y DIBEC? CURREN vDLfIAGE TAN-SFORMEH WWE SRiES EXIMTON,

APPLICATG- FILED AUGJt 1916.

Eatntedl Das@ 30, 19M.

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LGJMZJ f'E'TTINGEB, Utl' BADEN, SWITZERLAND, ASSIGNOR T0 KTENGESELLSCHAFT i BRUWN BO'QERI & CIE., OF BADEN, SWITZERLAND.

'DIRECT-CURRENT-VOLTAGE TRANSFORMER WTTH SERIES EXCETATN.

Lezama..

i. f., specification of Letters atent.

lratcnted Dec. 3), lllll.

Application led 'August 1, 1916. Serial No. 112.552.

To all whom, t may concern:

Be it known that I,- OsoAR GmNonR, a citizen of the Swiss Republic, residingl at No. t Riitistrasse, Baden, Switzerland, have invented certain new and useful Improvements in Direct-Current-Voltage Transformers with Series Excitation, of which the 'following is a specification.

This invention has for its object to provide an improved direct current voltage transformer composed of 'a motor and a dynamo, which Shall combine maximum simplicity of electrical connections and constructionV with absolute reliability in working' both for normal working and for'extraordinary conditions such as starting with a sudden connection to full potential. The improved transformer has also the advantage that the dynamo voltage remains practically unaltered even under large variations of load.

In the drawings:

Figure l illustrates the application of the improved transformer to railroad working,

Fig. 2 illustrates a modified form of the invention and Fig. 3 illustrates a further modification.

The essential' feature of the improved transformer consists in that both the motor' and the dynamo are excited mainly by th e.

main current'of the motor. The resulting simplicity of the electrical connections will be clearly perceived from Fig. 4l of the accompanying drawings. 'lhe scheme of connections shown in this figure illustrates the application of the limprinted transformer to railroad working. l

From the trolley line Lthecurrent passes through the trolley into he exciting winding: Sm ci? the motor M, and thence through the motor armature whencle it passes through the exciting winding' Sg of the dynamo G to earth. The armature of the motor M is connected mechanically to the armature of the dynamo G, and the effective current flows from the dynamo armature to' the currentconsuming devices V.

The magnetic dimensionsof the two niashines are such that simoly the 11o-load eurrent of the plete excitation of the two machines.

This circumstance is also a guarantee that the consequential high inductive resistance will completely exclude an impermissible cup is suiiicient for the comincrease of the starting current if the appa ratus' is placed in circuit suddenly under full voltage. This Jfact thus does away with the risk of the group burning out when there is no-load. The occurrence of the same risk when the circuit is interrupted at any point of the windings, is likewise rendered impossible by the very nature of the electrical connections.

For the purpose of preventie such a drop in the voltage at the termina s et' the dynamo G, as would otherwise happen in conm sequence of the increase in the' load under the influence of the drop in the number of revolutions and of the ohrnic losses, 'the magnetic dimensions of the two machines are also so chosen that one and the same alteration in the exciting ampere" turns will produce a greater alteration in. the number of the lines of force in'fthe dynamo than in the number of theflines of force in the motor- This result Iwhich; is due to the selection of the magnetic dimensions of the two machines may be further intensified and amplified by means eta compound winding K (Fig. 2) which' is imposed upon the enciting lield of the dynamo G and carries the effective current.

Instead of completely separating the electrical circuits of ,the two machines from each other as shown in Fig. l, they may be connected together. which is illustrated in Fig. 2,.has also the advantage of the well-known differential connection.

The use of this diterential connection for the purposes of the improved voltage transformer, is particularly suitable when the ratio between the primary and secondary voltages or the transformer is not very great. The same references are employed to indi cate corresponding parts in the two Figs. l

and 2. The illustrated embodiment of this invenl tion relates to a transformer group having separate armatures for motor and dynamo. ln some cases, however, and more especially where the load on the group does not vary within Wide limits, a single-armature trans--` former may be employed for the purposes of this invention.

When it isdesired to run the group at a "lll Such an arrangement speed which shall 'vary' as little possible,

this may be edected by adding to tlie exciting winding Sm of the motor an additional counter-compound winding H carrying the ede/tive current of the dynamo (i. Such an 'arrangement is illustrated in Fig- 3, where the Current passes from the l'rolley line L first through. the armature of the motor M, then through the exciting .vindinzgy Sg] of the dynamo (ij, then through the exciting winding Sm of the motor M, and' thence through the counter-Compound whirling H to earth.

ilihen the dynamo G if; loaded by the Curreiit-consunringr devices V, a current flows through the co1inter-Compound winding H in opposition to the current that flows through the latter from the trolley line li on starting, and the inset-mentioned current weakens the iehl oi the motor more and more as theioad inerear'ses, so that the drop iu the speed of the motor due to the increase in the load is thereby obviatcd. In this manner the aggregate or group is caused to run at practically' uneiminishcd speed and can be utilized :tor motive purposes.

TW hat i Claim is:-

l. in a direct current voltage transferium', theI combination of a motor7 a dynamo mechanically coupled to said motor, and means for energizing the motor and dynamo to produce the normal lio-load voltage of the dynamo solely by the motor el'lrrent.

In a direct current voltage transformer, the combination of a motor, 'a dynamo mcehanieally eoupied to said motor, and means whereby said motor'and said dynamo are both excited solely in accordance with the current of said motor, wherein the magnotie dimensions of the two machines are such that kthe no-load current oi the group is sufficient to excite completely the said two machines.'

3. In. a direct current voitage transformer, the combination of a motor, a dynamo ine-- elianieally coupled to said motor. and mea-neLm number of exciting ampere turns prodi'iees a.. greater alteration in the number of the lines of force in said dynamo than in said motor, whereby the effects of the speed drop and of the ohmie voltage drops are counter-- balanced by a proportionately larger alteration in the number of lines of force in Said dynamo.

4. in a direct current voltage translm'mer, the combination of a motor, a dynamo mechanically coupled te said motor, means whereby said motor and said dynamo are both excited solely in accordance with the current oi,l said motor, and an additional windingfor the magnetic field of said motor. carrying' current from said dynamo, :said additional winding' being arrangedv to oppose the action of the exciting winding` oit said motor, and weaken the field of .Said motor proportionately to the load current oi: said dynamo, whereby the speed ot' the transformer is maintained as near as poseible to' the high no-load speed, so that the consti-uo tional dimensions of Said dynamo may be made smaller iu correspondence to said high speed.

ln testimony whereof I have signed my name to this specification. l

v OSCAR GUTTINGER. lVitnesSes:

Cani. Guerri-in, OLGA Annie. 

